The present disclosure relates to a reception apparatus, a reception method, a demodulation apparatus, a demodulation method, and a program. More particularly, the disclosure relates to a reception apparatus, a reception method, a demodulation apparatus, a demodulation method, and a program for reliably performing a demodulation process.
In the past, digital broadcast reception apparatuses had receivable channels searched for and stored inside when the apparatuses were used for the first time. Based on the result of the channel search, the reception apparatuses then allowed channels to be selected (e.g., see Japanese Patent Laid-open Nos. 2002-101352 and 2004-222050).
During the channel search, the presence or absence of a broadcast at each modulation frequency is determined. If it is determined that a broadcast is present at a given frequency, transmission parameters of the channel corresponding to the frequency are decoded. The decoded transmission parameters are stored in a memory in conjunction with the modulation frequency. When this process has been performed on all modulation frequencies subject to search, the initial channel search is completed. At ordinary channel change time following the initial channel search, the transmission parameters stored in the memory are referenced and a desired digital broadcast is demodulated.
For example, the DTMB (Digital Terrestrial Multimedia Broadcast) standard is a typical terrestrial digital broadcasting system, among others.
FIG. 1 shows the frame format of the DTMB standard.
A frame according to the DTMB standard is made up of a header and a body. A symbol sequence of PN (pseudo noise) is inserted into the header. The body includes system information symbols (SI in FIG. 1) and data symbols (“Data” in FIG. 1), in that order. A symbol sequence obtained by encoding the transmission parameters as per predetermined rules is inserted into the 36-symbol system information at the beginning of the body.
As the transmission parameters, the DTMB standard stipulates FEC (Forward Error Correction) rates (e.g., 0.4, 0.6, 0.8), interleave lengths (e.g., 240, 720), or constellations (e.g., 4 QAM, 4 QAM-NR, 16 QAM, 32 QAM, 64 QAM), for example.